[Cbe-oss-dev] [PATCH] 64K support for Kexec

[Benjamin Herrenschmidt]

> But AS isn't relevant for Linux.  The PowerPC arch 2.03
> shows bits 0..15 as part of the VPN field.

Ugh ? The PPC Architecture Specification Book III is irrelevant to
Linux ? since when ? :-)

Now, as I said, there has been some changes in that area since 2.01
indeed, and while I don't have 2.03 (or later) at hand right now, I have
some of the RFCs leading to those changes and they do indeed seem to
imply that we shouldn't zero out those bits.

That makes it a bit annoying as that means we would need to add more
cpu-version specific code in __tlbie() and __tlbiel() ... so far,
however, every Book IV I've seen seems to show that those bits are
unused by tlbie(l), only lower order bits matter (which makes sense).

> It shouldn't matter much, those bits will be zero anyway
> as nothing implements that big an address space AFAIK.
> Some might get close though.

True. 

Cheers,
Ben.